A little bit on Pantographs

So I got a question on pantographs and did some Googling (thanks for your comment/question Tari btw). I'm not very familiar with them on a technical level, so I'm basically going to believe what the inter-web tells me. If anyone thinks what I'm writing here is a complete load of ___, please and please do leave some feedback!

Pantographs, well, for those who don't know what it is, it's the mechanism (with arms and linkages and etc.) on top of an electric train, that collects electricity from the overhead cantenary for the train's propulsion. Maybe I can say it's a fancy version of the trolley pole for trolley busses and old school streetcars. Below is a picture showing the parts of a modern Z-shaped single-arm pantograph from the German Wikipedia page of pantographs (there are many types out there, I won't go into history and all that now but they are linked here). Unfortunately I have not a clue what it's saying... je ne comprends pas Allemand and oh wait that wasn't even German.

Pantograph on the ICE3
The question was about the difference between Japanese pantographs (why they look funny and weird) compared to European ones. Tari's guess was right based on my quest on the web so far, it was all for the sake of reducing noise due to the stringent environmental laws of Japan. When looked at an European high-speed train, the look of a pantograph doesn't deviate too much from the German picture up there, but when we look at the pantograph on a Japanese high-speed train, sometimes we hardly recognize that it is a pantograph (like the expensive vortex generating pantograph from the Series 500 that goes straight up and down, according to the translated Japanese Wikipedia page, this particular pantograph was designed in conjunction with a Formula 1 parts manufacture, but it was too expensive to make and maintain so the design retired with the W Sets of the Series 500).

Wing-shaped pantograph on the Series 500 W Sets
Traditionally, the Japanese liked diamond shaped pantographs, as one could see on their older high speed trains. As speed of these trains increased, the noise emission of these trains was creeping beyond accepted limits by law. Earlier solution for this problem included a big shrouding around the pantograph, but it seemed to have only worked with speeds up to around 270 km/h or 170 mph (why? because these shrouding also made noise as air rushed onto them). More innovation was required to keep noise level down while increasing top speed of trains in service. After some money and research, the pantographs we saw on the latest and greatest Japanese high speed trains were born. In short, the new pantographs looked clean and minimalistic, with most components moved into aerodynamic housings or inside the roof of the train. Every component exposed to air was exposed for a good reason. Even the horn of the pantograph (curved ends of the slider or that top bar thingy that glide on the wire) had waved holes drilled into them to generate vortex and sound that suppresses the noise made by the pantograph at high speed.

The "shrouding" I was talking about, on a Series E2-0
Pantograph on the latest Series E5 with a 200 mph top speed
Pantograph on the Series N700 still has some "shrouding", top speed 186 mph
Well, hopefully that semi-answered the question. For the keeners who are interested, I did find some technical papers on noise reduction of high speed trains written by Japanese researchers (paper, paper, paper, more paper, more paper, more paper, more paper, more paper, book). Very intriguing to read (a little bit of background in vibrations and acoustics, which I don't have, may be required but interesting for anyone out there nonetheless).

Comments

Tari said…
Thank you for this post!! :D

Cheers from Italy,
Anonymous said…
interesting :)

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